This project is to organize an interdisciplinary team to work on RNA nanotechnology by constructing polyvalent RNA nanoparticles for specific targeting and delivery to cancer cells. RNA molecules can down-regulate specific gene expression in cancer cells. RNA is particularly attractive as a building block for bottom-up assembly in nanotechnology and nanomedicine. RNA can be manipulated as easily as DNA, but possesses the versatility in structure and function similar to that of proteins. RNA contains single-stranded stem-loops for intra- or inter-RNA interactions which can serve as mounting dovetails, providing advantages over external linking dowels in nanomachine assembly. This CNPP operation comprises of three major functions: the fundamental studies on therapeutic RNA nanoparticle construction; the conjugation and incorporation of therapeutic and targeting moieties to RNA nanoparticles; and the specific delivery of therapeutics to cancer cells. The team includes basic scientists with strong backgrounds in biomedical engineering, chemistry, and RNA and DNA nanotechnology; cancer biologists with extensive experience in ribozyme and siRNA delivery; and pharmaceutical cooperation focusing on RNA therapeutics with expertise in animal trials. The team will elucidate the principles underlying the RNA/RNA interactions in RNA nanoparticle assembly using phi29 motor pRNA system and RNA junction motifs to build polyvalent RNA oligomers containing aptamer, siRNA, ribozyme, ligand, imaging markers or drugs for cancer cell recognition and gene silencing. A new methodology of SELEX will be developed to screen for stable and high affinity RNA aptamers that target and enter cancer cells specifically. Simultaneous delivery and detection will be designed, combining therapy and detection of subsequent therapeutic effects on apoptosis. Approaches of crossover, chemical modification, and cross-linking will be applied to make RNA nanoparticles stable in vivo. Novel fermentation approaches and industry scale production methods will be developed to produce large-scale stable RNA for clinical applications. Animal trials on pharmacokinetics, bio-distribution, toxicity, gene silencing effects, and cancer cell killing will be carried out on animal models of lung cancer, ovarian cancer, liver cancer, and leukemia.